Ion booster for thrust generation

ABSTRACT

Ion booster for thrust generation. The invention pertains to electrical propulsion generated by the rapid acceleration of ions between asymmetrical electrodes. The invention is applicable for propulsion generation in atmospheric and space environments.

FIELD OF THE INVENTION (TECHNICAL FIELD)

The present invention relates to propulsion generating technologies.Specifically, to propulsion generated by electrical sources (electricpropulsion) with the use of electrodes subjected to a potential(voltage) differential.

Generation of thrust from electrodes subjected to a potentialdifferential was first discovered in 1928 by T.T. Brown. Since then,numerous inventions have emerged using this principle to generate thrustto propel vehicles. Inventions have used different electrodesarrangements and configurations to increase the thrust levels. However,the basic principle used by Brown has remained unchanged in theseinventions.

Three pillars will drive the aerospace market in the next ten years: 1)autonomous flying; 2) aircraft communications; and 3) electricpropulsion. Additionally, as NASA continues to investigate thefeasibility of hybrid and all-electric aircraft for future commercialuse, several key electric power-related components and materials need tobe developed or refined to meet the ambitious power goals established bythe agency’s Advanced Air Transport Technology (AATT) Project.

The U.S. Department of Defense has great interest in ion thrusters forspace application. As stated on the SBIR announcement AF192-044 futureDoD spacecraft will need greater agility to change orbits for missionrequirements or to avoid the increasing hazards in crowded orbits. Anagile spacecraft is one that can make an orbital change while maximizingpropulsive life through propellant conservation. Agility requires, atminimum, propulsion concepts that are able to trade specific impulse(Isp) with thrust over a wide range as mission needs require. Shortnotice needs would require high thrust at the expense of propellant.Mission needs that have less severe time constraints can use high Ispand conserve propellant. However, a truly agile spacecraft will requireboth high thrust and high Isp simultaneously, at least for short periodsof time,

Thrust using electrodes at high potential difference is achieved byusing electrodes of significant different sizes having opposite voltagepolarity. A smaller electrode (having higher current density) attractsexisting opposite charged ions and/or electrons from the surroundingmedium (i.e. air, nitrogen, xenon gas) at high speeds. On their path,these ion or electrons collide with neutral molecules. These collisionscause the neutral molecules to gain or lose an electron. The impactedmolecules now polarized are attracted to the larger electrode at highspeed and their acceleration generates thrust.

It’s important to note that ionic wind is generated by these high-speedtraveling molecules, but it is not the main source of propulsion (theyhave a lower contribution by several orders of magnitude).

So far, the use of high voltage electrodes to generate thrust has onlybeen successful in space applications. Spacecraft use Xenon gas as themedium (which has a large molecular weight) to increase the momentumgenerated when molecules are accelerated. Low levels of thrust aregenerated but since there are no friction forces in space, the thrustersare used for long intervals until the desired velocity is achieved.However, spacecrafts pay the weight penalty of carrying the Xenon gas asfuel.

SUMMARY OF THE INVENTION

In atmospheric conditions, generation of useful thrust levels have notbeen achieved due to the limitation of using air as the medium. Thelimitations are due to the air’s dielectric breakdown voltage and theavailability of ions in the atmosphere.

Embodiments of the present invention herein presented boost the thrustlevels of an ion thruster by extracting electrons from the electrodes.This is achieved by overcoming the work function of the electrodematerial. As electrons are extracted, they generate additional collisionwith the surrounding medium thus increasing the number of chargedmolecules. The acceleration of the increased number or charged moleculesand the electrons increases the thrust levels of the ion thruster.

The embodiments of the invention are applicable to any medium (i.e.Xenon gas, nitrogen, air). Notably, the use of the embodiments of thepresent invention in atmospheric conditions increases the thrust levelsto a point which makes ion thrusters a viable option for electricallypowered aircraft.

In an embodiment a system is disclosed which includes one or moreprimary electrodes; at least one secondary electrode; a high voltagepower supply having a ground output operationally connected to said oneor more primary electrodes, said high voltage power supply furtherhaving a positive output operationally connected to said at least onesecondary electrode; and an energy source to overcome the work functionof a material of said one or more primary electrodes when energized.

In an embodiment, the energy source can comprise a secondary powersupply operationally connected in a closed circuit to said one or moreprimary electrodes to increase the temperature of said one or moreprimary electrodes when energized. Alternatively, the energy source cancomprise a heating element for heating said one or more primaryelectrodes or a UV light source in proximity to said one or more primaryelectrodes. Further, combinations of the three energy sources can beused.

In various embodiments the one or more primary electrodes can comprise aceramic material, a semi-conductor material and a conductive alloymaterial, or various combinations of those materials.

An embodiment comprises multiple cells arranged in a linearconfiguration, each cell one of the systems described above.Alternatively, multiple such cells can be arranged in a cylindricalconfiguration.

In an embodiment a method is disclosed for generating thrust using anion thruster system having one or more primary electrodes, at least onesecondary electrode, a high voltage power supply, and an energy sourceto overcome the work function of a material of said one or more primaryelectrodes when energized, the method comprising: supplying high voltagepower to said one or more primary electrodes and said at least onesecondary electrode with a ground output of said high voltage powersupply supplying the high voltage power to said one or more primaryelectrodes and a positive output of said high voltage power supplysupplying the high voltage power to said at least one secondaryelectrode; and applying energy from the energy source to overcome thework function of a material of said one or more primary electrodes.

In embodiments applying energy from the energy source can compriseapplying electrical power to said one or more primary electrodes from asecondary power supply to heat the one or more primary electrodes, usinga heating element for heating said one or more primary electrodes andapplying UV radiation to said one or more primary electrodes or variouscombinations of the foregoing methods for applying energy from theenergy source.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, illustrate one or more embodiments of the presentinvention and, together with the description, serve to explain theprinciples of the invention. The drawings are only for the purpose ofillustrating one or more embodiments of the invention and are not to beconstrued as limiting the invention. In the drawings:

FIG. 1 is a simplified schematic of an embodiment of the invention;

FIG. 2 shows a simplified schematic of the principle of the embodimentsof the invention;

FIG. 3 is a schematic of an embodiment of the invention using conductivemetal alloy electrodes;

FIG. 4 is a schematic of embodiments of the invention using a ceramic orsemi-conductive electrode;

FIG. 5 is a schematic of an embodiment of the invention using UV (ultraviolet) light radiation;

FIG. 6 is an embodiment of the invention on a single linear cellconfiguration;

FIG. 7A is an embodiment of the invention comprising multi-cellconfiguration for linear thrusters;

FIG. 7B is an embodiment of the invention comprising multi-cellconfiguration for cylindrical thrusters;

FIG. 8 shows the experimental set up for testing an embodiment of theinvention;

FIG. 9 shows in more detail the constant springs used in the set-up ofFIG. 8 to help maintain the tension of the electrodes regardless oftheir temperature;

FIG. 10 shows the results from the experimental set up of FIG. 8 where abaseline was created using the high-power supply only and was thencompared to the thrust improvement when the secondary power supply wasadded to heat up the small electrodes;

FIG. 11 shows the improvement as a percentage of thrust increase.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the embodiments ofthe invention. However, upon studying this application, it will beunderstood by one of ordinary skill in the art that the embodiments maybe practiced without these specific details. For instance, well knownoperation or techniques may not be shown in detail. Technical andscientific terms used in this description have the same meaning ascommonly understood to one or ordinary skill in the art to which thissubject matter belongs.

As used throughout this application, the term “or,” as used herein, isused in its inclusive sense (and not in its exclusive sense) so thatwhen used to connect a list of elements, the term “or” means one, some,or all of the elements in the list. Conjunctive language such as thephrase “at least one of X, Y, and Z,” unless specifically statedotherwise, is understood to convey that an element may be either X, Y,Z; X and Y; X and Z; Y and Z; or X, Y, and Z (i.e., any combination ofX, Y, and Z). Thus, such conjunctive language is not generally intendedto imply that certain embodiments require at least one of X, at leastone of Y, and at least one of Z to each be present, unless otherwiseindicated.

References herein to the positions of elements (i.e. "top," "bottom,""FWD," “AFT, "above," “below”) are merely used to describe theorientation of various elements in the figures. It should be noted thatthe orientation of various elements may differ according to otherexemplary embodiments, and that such variations are intended to beencompassed by the present disclosure.

Embodiments of the present invention provide a technology-based solutionthat can overcome existing problems with the current state of the art ina technical way to satisfy an existing problem for Private, Commercial,and Military Transportation for Atmospheric and Space travel. Known ionthruster art only optimizes the basic principle discovered and patentedby T.T. Brown in 1928. Embodiments of the invention can use a newphysical principle which boosts the thrust of ion thrusters tounprecedented levels by extracting electrons from the electrode[s].Embodiments of the invention comprise ion thruster cells that may haveseveral configurations. In the various possible configurations, ionthruster cells generally provide superior thrust levels than the stateof the art by extracting electrons from the electrode[s] disclosedherein to increase the amount charged ions created by collisions betweenthe electrons and the neutral molecules of the medium. The electrons arealso accelerated. This acceleration of electrons' mass also contributesto the increase in thrust.

Embodiments of the invention can use three physical principles togenerate thrust: asymmetric electrodes (different sizes) subjected to apotential differential, electrostatic forces created by potentialdifferential, and overcoming the work function of the electrode’smaterial.

Referring now to FIGS. 1-5 , schematics are shown of different aspectsand various embodiments of the invention comprising three possibleexemplary energy sources to overcome the work function of the materialof a smaller electrode, namely: 1) heating by electricity, 2) secondaryheating; and 3) radiation from an UV light source. In the variousembodiments of the invention, electrons are pulled from an electrode byovercoming the work function of its material. FIGS. 7A and 7B showembodiments of the invention: linear stackable cells and cylindricalstackable cells.

Referring in more detail to FIG. 1 , according to an embodiment,electrode 1 and electrode 2 are preferably made of conductive alloys. Inone embodiment electrode 1 (also referred to as the primary electrode)is preferably smaller than electrode 2 (also referred to as thesecondary electrode). In one embodiment, high voltage power supply 3 isconnected to electrodes 1 and 2. The ground (negative) output of highvoltage power supply 3 is operationally connected to electrode 1 and thepositive output of high voltage power supply 3 is operationallyconnected to electrode 2. The operational connections can beaccomplished directly (e.g., direct wiring) or indirectly (e.g., havingintervening elements such as amplifiers or other circuitry). Electrode 1and electrode 2 are preferably attached to structure 5. When electrode 2is larger than electrode 1, thrust is generated by the asymmetricelectrodes subjected to a large potential difference. Additionally,electrostatic attractive forces are created between the electrodes butare transferred to structure 5 and do not contribute to the thrustgenerated.

In one embodiment, electrode 1 is also connected to secondary powersupply 4. The material of electrode 1 is preferably such that itincreases temperature as the secondary power supply is energized. Oncesecondary power supply 4 is energized, the temperature of smallerelectrode 1 begins to increase and starts approaching the work functiontemperature of its material. Additionally, the electrostatic forcescreated between the electrodes contribute to overcoming the workfunction of electrode 1. Electrons are pulled from the surface ofelectrode 1 by the increased temperature and the electrostatic forces.

FIG. 2 shows the electrons being pulled from the surface of electrode 1,which, in one embodiment, are attracted by larger electrode 2 that has alarge positive voltage potential. The electrons leaving smallerelectrode 1 travel at a very high speed thru medium 7. The medium can beair, nitrogen gas, xenon gas or other types of gases. The molecules inmedium 7 are impacted by the electrons leaving electrode 1 which createadditional ions in medium 7. Newly created negatively charged ions areaccelerated towards larger electrode 2, which significantly increasesthe thrust generated by the system. Electrons leaving electrode 1 mayalso be accelerated toward electrode 2 without colliding with neutralmolecules.

FIG. 3 shows the schematic of an embodiment with the addition ofconstant force element 6. As the temperature of the electrode 1increases, it expands which increases its length. Constant force element6 ensures that electrode 1 remains in constant tension regardless of itstemperature.

Generally, the mechanism of overcoming the work function of a materialby increasing its temperature is termed Thermionic Emission. Materialsused for the electrode 1 can be metal alloys, ceramics, andsemi-conductors. In the case of ceramics and semiconductors, it isnecessary to heat up the material for it to become conductive ofelectricity. In one embodiment, this is accomplished by introducingheating element 17 shown in FIG. 4 . Once the material has been heatedup using heating element 17 it becomes conductive and secondary powersupply 4 can be energized and the system will operate as previouslydescribed. At this point, heating element 17 can be removed. Materialsrequiring heating prior to becoming conductive include, but are notlimited to, Yttrium, Zinc dioxide, and other materials capable ofreleasing higher quantities of electrons to the medium.

In another embodiment, the work function of a material is overcome by UVlight radiation. FIG. 5 shows a schematic of an embodiment of theinvention using UV light source 8 to radiate electrode 1 to contributein overcoming its material work function.

FIG. 6 shows an embodiment in a single cell configuration. Inside thecell, the electrodes are fixed to a structure and the medium is providedat the intake of the cell. Any of the earlier described arrangements canbe implemented in the shown configuration.

FIG. 7A shows an embodiment in a multi-cell linear configuration andFIG. 7B in a cylindrical configuration. They can be stacked or placedconcentric to each other. Any of the earlier described arrangements canbe implemented in the shown configurations.

In addition to the embodiments presented, the thruster’s configurationcan include a plurality of electrode arrangements to optimize the thrustgenerated. Embodiments of thrusters can also be multistage where asecond, third or more thrusters are placed in an array one behind theprevious.

The various embodiments of the present invention can significantlyincrease the thrust levels in an ion thruster by extracting electrons ofan electrode. The increased levels of thrust enable the use of the ionpropulsion technology in atmospheric conditions and increases theperformance of ion thrusters for space travel. Embodiments of theinvention provide a major break-thru in the field of atmosphericelectric propulsion making the use of the ion thrusters technologies afeasible option for generating thrust. For space travel, the embodimentsof invention provide higher thrust level which enable spacecraft toperform agile quick response maneuvers and increases the velocity ofspacecrafts shortening mission times.

Industrial Applicability

The invention is further illustrated by the following non-limitingexamples.

Example 1

An embodiment was implemented using the experimental set-up shown inFIG. 8 . The experimental set-up comprised two top electrodes and onebottom electrode. The top electrodes had diameters of 0.0005 inches, andthey were made out of Nichrome 80 material. The bottom electrode had adiameter of 0.1875 inches, and it was made from cardboard foam and woodcovered in aluminum foil. All electrodes were made from conductivematerial. All electrodes had a length of 12 inches.

The high power supply had a maximum delivery voltage of 30.7 KV DC at0.5 milli-Amps. The high voltage power supply was used to its maximumrated capacity. The secondary voltage power supply had a maximumdelivery voltage delivery of 60 V DC at 5 Amps. The secondary powersupply was used to a voltage of 32 V DC.

The electrodes were fixed to a wood structure which was mounted on ascale. The scale recorded the amount of upward thrust achieved by thesystem for given voltages (mass multiplied by gravity).

The top electrodes were fixed at one end of the structure and weremounted onto constant springs at the other end to ensure their tensionremain constant regardless of the thermal expansion of the topelectrodes when their temperature increased (See FIG. 9 ).

The top electrodes were connected to the ground (negative) of the highvoltage power supply. The bottom electrode was connected to the positiveoutput of the high voltage power supply.

The top electrodes were also connected in parallel to the secondarypower supply at each end. This created a close circuit with thesecondary power supply.

The experiment was first conducted by only energizing the high voltagepower supply and thrust measurements were recorded by varying the outputof the high voltage power supply from 10 KV to 30.7 KV.

The experiment was then repeated but with both power supplies (highvoltage power supply and secondary voltage power supply) energized.Measurements of thrust were recorded by varying the output of the highvoltage power supply from 10 KV to 30. The secondary power supplied setto 32 V DC and remained unchanged.

The difference of the measurements between the first and secondexperiment demonstrate the improvement that embodiments of the inventioncan provide to the level of thrust generated.

FIG. 10 shows the experimental results showing the contribution of theimprovement in the increased of thrust levels. FIG. 11 shows thepercentage of improvement in the thrust achieved. Surprisingly, resultsshowed an unexpected maximum contribution of 254.4% for 18KV inputvoltage from the high voltage power supply.

The preceding example was for a single cell thruster. The example can berepeated using a plurality of electrodes configuration and a pluralityof voltage polarities supplied to the electrodes.

The preceding example can be repeated with similar success bysubstituting the electrode materials with ones having lower workfunction which may require heating the top electrodes prior toenergizing the secondary voltage power supply. The example can also berepeated with materials which work function can be reached by UV lightirradiation.

Although the invention has been described in detail with particularreference to these described embodiments, other embodiments can achievethe same results. Variations and modifications of the present inventionwill be obvious to those skilled in the art and it is intended to coverin the appended claims all such modifications and equivalents. Theentire disclosures of all references, applications, patents, andpublications cited above are hereby incorporated by reference.

What is claimed is:
 1. An ion thruster system comprising: one or moreprimary electrodes; at least one secondary electrode; a high voltagepower supply having a ground output operationally connected to said oneor more primary electrodes, said high voltage power supply furtherhaving a positive output operationally connected to said at least onesecondary electrode; and an energy source to overcome the work functionof a material of said one or more primary electrodes when energized. 2.The ion thruster system of claim 1 wherein said energy source comprisesa secondary power supply operationally connected in a closed circuit tosaid one or more primary electrodes to increase the temperature of saidone or more primary electrodes when energized.
 3. The ion thrustersystem of claim 2 wherein said one or more primary electrodes comprise aconductive alloy material.
 4. The ion thruster system of claim 1 whereinsaid energy source comprises a heating element for heating said one ormore primary electrodes.
 5. The ion thruster system of claim 4 whereinsaid one or more primary electrodes comprise a ceramic material.
 6. Theion thruster system of claim 4 wherein said one or more primaryelectrodes comprise a semi-conductor material.
 7. The ion thrustersystem of claim 1 wherein said energy source comprises a UV light sourcein proximity to said one or more primary electrodes.
 8. The ion thrustersystem of claim 7 wherein said one or more primary electrodes comprise aceramic material.
 9. The ion thruster system of claim 7 wherein said oneor more primary electrodes comprise a semi-conductor material.
 10. Theion thruster system of claim 1 further comprising a constant forceelement operationally connected to said one or more primary electrodesto maintain a constant tension on said one or more primary electrodesregardless of their temperature.
 11. A multi-cell ion thruster systemcomprising multiple cells arranged in a linear configuration, each cellcomprising an ion thruster according claim
 1. 12. A multi-cell ionthruster system comprising multiple cells arranged in a cylindricalconfiguration, each cell comprising an ion thruster according claim 1.13. The ion thruster system of claim 10 wherein said constant forceelement is constant force tension springs.
 14. A method of generatingthrust using an ion thruster system having one or more primaryelectrodes, at least one secondary electrode, a high voltage powersupply, and an energy source to overcome the work function of a materialof said one or more primary electrodes when energized, the methodcomprising: supplying high voltage power to said one or more primaryelectrodes and said at least one secondary electrode with a groundoutput of said high voltage power supply supplying the high voltagepower to said one or more primary electrodes and a positive output ofsaid high voltage power supply supplying the high voltage power to saidat least one secondary electrode; andapplying energy from the energysource to overcome the work function of a material of said one or moreprimary electrodes.
 15. The method of claim 14 wherein applying energyfrom the energy source comprises applying electrical power to said oneor more primary electrodes from a secondary power supply to heat the oneor more primary electrodes.
 16. The method of claim 14 wherein applyingenergy from the energy source comprises using a heating element forheating said one or more primary electrodes.
 17. The method of claim 14wherein applying energy from the energy source comprises applying UVradiation to said one or more primary electrodes.